This invention relates to a die casting machine and more particularly apparatus for automatically measuring the injection speeds of an injection cylinder of the die casting machine.
In the operation of a die casting machine, it is known that the continuous operation thereof has been performed by presetting the starting positions for low and high speed injections and the positions at which the injection speed is changed from low to high in accordance with the desired size, shape and thickness of the cast products.
Usually, although a test casting operation has been performed to find out necessary conditions for continuously operating the die casting machine, the starting positions for the low and high speed injections and the position at which the injection speed is changed from low to high are properly determined by repeatedly observing the qualities of the cast products. However, in an actual continuous casting operation of the die casting machine, the injection speed does not often coincide with that obtained in the test casting operation because of disturbances such as an insufficient lubrication for the plunger and the sleeve of an injection unit, irregular motion and seizure between the plunger and sleeve, and the variation in the viscosity of the oil used for operating an injection cylinder. Therefore, it is required to readjust the injection speed in the actual continuous operation of the die casting machine.